Ukrainian president Petro Poroshenko (left) and Mikhail Saakashvili are greeted by crowds in Odessa on Saturday.
Photograph: Mykola Lazarenko/AP

Petro Poroshenko, the president of Ukraine, has appointed former Georgian president Mikheil Saakashvili to be governor of Ukraine’s southern Odessa region, in a surprise move that is certain to raise hackles in Moscow.

At least three people were killed in the east of the country where government forces are fighting Russian-backed separatists.

Poroshenko made the announcement of Saakashvili’s appointment standing alongside the Georgian at a ceremony in Odessa, where he described him as “a great friend of Ukraine“. He granted Saakashvili Ukrainian citizenship to facilitate the move.

The security of the Black Sea city of Odessa and its surrounding region has become a growing concern for Ukrainians since a separatist conflict broke out in eastern Ukraine following Russia’s annexation of Crimea further along the coast last year.

Saakashvili replaces Ihor Palytsia, a businessman who was appointed governor in May last year after more than 40 people, most of them pro-Russian sympathisers, died in a fire in the port city during a confrontation with pro-western demonstrators.

Poroshenko, who is pursuing a course of European integration to take his country out of the Russian orbit, has appointed several non-Ukrainian nationals to government posts, including the finance ministry where US-born Natalia Yaresko has taken over. But this is the first non-Ukrainian by birth to be named to head what is in effect a provincial government.

Saakashvili is widely credited with carrying out radical reforms in Georgia and cracking down on corruption during his term in office from 2004-2013. But the present Georgian leadership has accused him of abuse of power and has asked for his extradition. He denies any wrongdoing and says charges against him are politically motivated.

Like Poroshenko, Saakashvili, whose country fought a brief war with Russia in August 2008, is a strong advocate of Nato and European Union membership for his native Georgia and for Ukraine.

His appointment drew immediate derision in Moscow. The Russian prime minister, Dmitry Medvedev, tweeted: “Saakashvili – head of Odessa region. The Chapiteau show goes on. Sad Ukraine ...“. The ‘chapiteau show’ is a Russian way of referring to circus routines.

Poroshenko expressed confidence that Saaksahvili would bring discipline and carry out much-needed changes in the region. “The people of Odessa should soon feel that their living standards have been raised,” he said.

In fresh violence in the separatist-minded eastern territories, Kiev’s military reported that one serviceman had been killed and another wounded in attacks by the rebels despite a February ceasefire.

A father and his son were also killed when they triggered a trip wire attached to a grenade while walking in government-controlled territory near the city of Luhansk, the regional head said.